1. Field of the Invention
The present invention relates to a mobile communication system, a mobile communication method, a radio network controller, a radio base station and a mobile station, employing a configuration in which a radio device transmits, to mobile stations by use of broadcast communication, emergency information transmitted from a distribution server.
2. Description of the Related Art
Heretofore, there have been known mobile communication systems for transmitting, to mobile stations, emergency information such as earthquake information or “tsunami” information issued by a public office, a local government, or the like, by use of broadcast communication such as a cell broadcast service (hereinafter, referred to as a “CBS”) or a multimedia broadcast/multicast service (hereinafter, referred to as an “MBMS”).
Specifically, in such a mobile communication system for transmitting the emergency information, a radio network controller RNC is configured to transmit the aforementioned emergency information to mobile stations located in a particular coverage area, by use of a traffic channel for broadcast communication such as a common traffic channel (CTCH) or an MBMS traffic channel (MTCH). Here, the emergency information is received from a terminal device of a public office, a local government, or the like, via a distribution server.
In such conventional mobile communication systems for transmitting the emergency information, there is, however, a problem that long delay time is required for the emergency information to reach the mobile station. This problem occurs since a radio network controller needs to transmit information via various channel, before transmitting information via a traffic channel for broadcast communication such as a CTCH or MT CH.    (Non-Patent document 1) 3GPP TS23.041    (Non-Patent document 2) 3GPP TS23.246